Molecular characterization of TRADD in GIFT tilapia (Oreochromis niloticus).

Tumor necrosis factor receptor type 1-associated death domain protein (TRADD) is a crucial adaptor in the TNF signaling pathway. The role of fish TRADD remains less understood, compared with that of mammals. In the present study, TRADD of genetically improved farmed tilapia (GIFT, Oreochromis niloticus) was characterized. The GIFT TRADD encoded a putative protein of 291 amino acids, containing an N-terminal domain and C-terminal death domain. qPCR analysis revealed that GIFT TRADD was ubiquitously expressed in all selected tissues and upregulated in spleen following lipopolysaccharide (LPS) or polyriboinosinic polyribocytidylic acid (polyI:C) stimulation and tilapia lake virus (TiLV) infection. Overexpression of GIFT TRADD significantly inhibited expression of TiLV-S10 in TiLV infected tilapia brain (TiB) cells, and increased the expressions of melanoma di-erentiation-associated gene 5 (MDA5), Mx1, NF-κB and interferon regulatory factor (IRF) 3 in TiB cells. These results indicated that GIFT TRADD had antiviral and immunomodulatory roles, providing basis for understanding the TNF signaling pathway in GIFT.